The present invention relates to improvements made to gas cooking appliances equipped with a top plate having at least one region for the attachment of an injector of a gas burner and for supporting a head of the said burner coaxial with the said injector and above the said plate with primary air being drawn in from on top of the plate.
Habitually, the gas burner is surmounted by a grating itself resting on the top plate and able to support the vessels with their bottoms situated at a given height over the burner. Whatever the construction of the grating (cast iron grating, steel wire grating), flames coming into contact with an element (finger, rod) of the grating leads to increased CO emissions and these may become excessive with regard to the requirements laid down in the standards and health requirements.
In order to avoid, or at least to lessen, this drawback, it is known practice for the formation of flames under the metal parts of the grating to be prevented: this is obtained by eliminating certain flame orifices on the periphery of the burner head.
However, for such an arrangement to prove effective, it is then necessary for the burner head to be positioned correctly so that the regions which have no flame orifices lie exactly under the metal parts of the grating. Now, it is not, in practice, possible to rely entirely upon the user to put the burner head back in the correct angular position after a cleaning operation.
Furthermore, independently of the correct angular positioning of the burner head with respect to the grating, it is also essential that the burner head rest on the top plate in a situation of as perfect as possible coaxiality with the injector fixed to the plate. Here again, it is not possible to rely entirely upon the user to ensure this coaxiality.
It is therefore essentially an object of the invention to provide an improved arrangement of a gas burner of the kind in question, so that the correct positioning of the burner head no longer relies simply on the free will of the user, the means implemented to these ends having, however, not to lead to any appreciable complication in manufacture or any significant additional cost.
To these ends, a cooking appliance as mentioned in the preamble is characterized, being arranged in accordance with the invention, in that the aforementioned region of the top plate, whether it be formed integrally with the plate or attached, has a non-circular contour and in that the burner head has legs by which it rests on the aforementioned region of the top plate, the number and arrangement of which legs are such that they collaborate with the sides of the said non-circular contour of the said region so that the burner head can occupy only a determined and limited number of angular positions while at the same time being arranged coaxial with the injector and so that, for any incorrect positioningxe2x80x94in terms of orientation and/or in terms of centringxe2x80x94of the head, the latter rests on the top plate such that it is inclined and that the incorrectness is thus visible.
In a preferred embodiment, the said region of the top plate is a non-circular plateau surmounting the rest of the said plate, and the number and arrangement of the legs of the burner head are suited to these legs collaborating with the lateral faces of the non-circular pyramid bordering the plateau.
The arrangements of the invention may also be implemented by contriving for the said region of the top plate to be a non-circular dish extending under the rest of the said plate, and for the number and arrangement of the legs of the burner head to be suited to these legs collaborating with the lateral faces of the non-circular pyramid bordering the dish.
The arrangements of the invention may also be implemented in cases where the said region of the top plate is coplanar with the rest of the plate and for example comprises hollow indentations distributed about the said non-circular contour and in which the ends of the legs of the burner head rest.
A preferred, although non-limiting, embodiment of the foregoing arrangements consists in the aforementioned region of the top plate having a polygonal contour.
In this case, a preferred embodiment of such an arrangement may consist in the said region of the top plate having a rectangular shape and in the number of possible correct positions of the burner head being two. Another preferred embodiment of these arrangements may consist in the said region of the top plate having a square shape and in the number of possible correct positions of the burner head being four. Of course, other configurations (region of pentagonal, hexagonal or octagonal shape in particular) are conceivable.
However, the aforementioned region of the top plate can just as easily be elongate of revolution, particularly oval or elliptical, with the same advantages being obtained.
The arrangements according to the invention make it possible simultaneously to ensure physical error-proofing regarding the angular positioning of the burner head and its coaxiality with respect to the injector while at the same time allowing a simple visual check (burner head sitting crooked on the top plate) in the event of incorrect positioning (poor angular positioning, lack of coaxiality with the injector).
The means implemented are simple and have practically no impact on the cost of manufacture since the configuration (flat, hollow or plateau-shaped) of the region concerned of the top plate is down to the actual design of the burner and of the cooking appliance and since arranging the burner with the primary air supply from on top of the plate entails having legs: implementation of the arrangements of the invention has an impact only on the geometric shape given to the aforementioned region and on the geometric arrangement of the legs in relation to the shape of the support region.